Topical delivery of drugs is a very useful method for achieving systemic or localized pharmacological effects. The use of microneedles has great advantages, in that intracutaneous drug delivery can be accomplished without pain and without bleeding. Of particular relevance to the present invention are hollow microneedles, which each comprise a protrusion and a passageway therethrough. The passageway allows fluids to pass from an internal chamber through the passageway and into a patient's skin or, alternatively, body fluid samples to pass from a patient through the passageway and into an internal chamber.